This invention is directed to the providing of a selectively adjustable, variable-width-beam light apparatus which is designed to be mounted on a helmet or other suitable headgear that is to be worn by a person and thereby free both hands for other functions. Two general areas of use for lights mounted on a person's headgear are deep tunnel or shaft mining or exploration operations and hunting, although it will be readily recognized that there are many other specific instances where lighting apparatus of this type may be found to be particularly advantageous. The capability of beam width adjustability from a maximum width beam for large area illumination to a minimum width beam for relatively small area illumination greatly enhances the usefulness of a lighting unit. The additional capability of angular adjustment of the central axis of the light beam with reference to a support or a surface further enhances the usefulness of such a lighting apparatus by enabling the wearer of the headgear to direct the light beam to a desired point or area as deemed most advantageous to the wearer regardless of head position or position of the headgear on the person's head.
Lighting apparatus having variable-width-beam capability has been previously devised to either emit a narrow beam for pinpoint illumination of an object or to emit a relatively wide beam to function as a floodlight to illuminate a larger area, or to emit a light beam of intermediate width. The known lighting apparatus having a variablewidth-beam capability incorporate what is generally described as a primary housing in which a light emitting source such as an incandescent electric lamp is mounted and a reflector unit. The reflector unit is provided with a reflecting surface of parabolic configuration with a difference in beam width being achieved through selective positioning of the relative position of the lamp along the longitudinal axis of the reflector extending through the apex of the parabola. In the known light apparatus, the lamp is mounted either in a fixed position in the primary housing and the reflector is selectively displaced along a longitudinal axis with respect to the lamp, or the reflector is mounted in a fixed position on the primary housing with the lamp being selectively positionable along the longitudinal axis. Structures using the movable reflector technique generally employ a telescopic tube construction with the one tube carrying the reflector and being axially displaceable with respect to the other tube carrying the lamp as by a screw-threaded interconnection. Operation of such structures requires that one part of the housing be rotated relative to the other necessitating that at least that part of the housing be substantially fully accessible to permit a person to grip the housing. Prior structures using the movable lamp technique have included an internal, axially displaceable support for the lamp mounted within the primary housing and having relatively complex mechanisms projecting outwardly of the primary housing to permit manual manipulation.
A disadvantage of the known displaceable lamp structures is the relative complexity of the mechanism and/or difficulty of operation. A disadvantage of known lighting apparatus using either structural technique described for achieving the necessary axial displacement is the substantial longitudinal dimension required to obtain the desired variability in beam width. Physical size of the apparatus, particularly length, is important with respect to such structures mounted on headgear.
Another significant disadvantage of the known lamp structures having variable-width-beam capability is their lack of adjustability as to the angle of the emitted light beam and the light support such as a person's headgear. It is particularly advantageous in the case of a headgear mounted light to be able to adjust the beam to a selected angular position in a vertical plane.